Safety switch for liquid cooled engines



Nov. 6, 1951 Filed Oct. 26, 1949 Z7 I6 M r- III"; Hu s?"- mu;

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INVENTOR. Len SAMUEL, BY

Patented Nov. 6, 1951 UNITED- STATES PATENT OFFICE SAFETY SWITCHIFOR LIQUID COOLED ENGINES This invention relates to new and useful im-' provements in safety devices for the internal combustion engines of automotive vehicles, and, more particularly, the aim is to provide, especially for'use in liquid-cooled engines, a novel and valuable automatic temperature-responsive switch which, functioning when the temperature of such liquid, as that constituting the common water jacket, reaches a motor overheating temperature or one dangerously close thereto, thus functions to stop operation of the motor.

As preferably installed, the new device, incorporating a pair of normally closed contacts, is interposed, by way of said contacts and connections thereto passing through the sealed interior of the device, in the primary circuit between the coil and the ignition switch of the electrical installation operably associated with the engine.

The present invention is to be sharply distinguished from such proposals as might involve arrangements wherein the temperature of the engines cooling liquid wouldv be transmitted indirectly,'that is, by plural-stage or plurally-relayed radiation and/or convection, to a thermostatic element; or wherein, as in such a situation as that lastreferred to, a thermostatically operating heat-responsive device would be attached to or close to a spark-plug; or wherein a perma nent or other magnetic means would be relied on for quick breaking of a pair of normally closed contacts in aid of the avoidance of arcing at the contacts.

According to the instant invention, a simple, compact, light-weight yet rugged and long-lived but nevertheless a relatively inexpensive device is provided; which device, indeed, so far as diminutive size is concerned, may have merely a fraction of the bulk of an ordinary spark-plug; which at the same time includes a working subdivision so incorporated that in working position it is projected directly into the cooling liquid in any selected one of a large plurality of possible locations interior to the cavitation means present in the engine for confining the cooling fluidduring its circulation consequent upon operation of the engine; which, also, may be depended on to function always as intended, whetherits said working subdivision is at any portion there'- of immersed inthe liquid or, because of lack of attention to a previous need to replenish the liquid, is above the surface of the liquid; which, furthermore, may be simply and easily given. its said selected location, as at some convenientpoint on the main structure of the engine; and

Claims. (01. 200138) which is uniquely capacitated to avoid oxidation of the contacts incidental to arcing thereat when they automatically separate due to a darigerous temperature having been reached by the cooling liquid. v

For further comprehension of the invention,

of the objects and advantages thereof, reference will be had to the following description and accompanying drawings, and to the ap-' pended claims in which the various novel features of the invention are more particularly set forth.

In the accompanying drawings forming a material part of this disclosure:

Fig. 1 shows a now favored embodiment of the invention in side elevation, and drawn to actual scale so far as a now approved size is concerned.

Fig. 2 is a somewhat enlarged similar view.

with a minor possible modification indicated iii dot and dash; this view also including, schematically, part of an electric circuit.

Fig. 3 is an enlarged axial sectional view of the safety device.

Fig. 4 is a partial sectional view showing the motor block and cylinders.

Fig. 5 is a view similar to the lower portion of Fig. 3, but illustrating a modification of the present invention.

Referring now to the drawings more in detail, and by reference numerals, the embodiment of the new device herein illustrated is as a whole designated IG.

Said device I 0 incorporates a main shell ll,

1 desirably of a suitable metal readily machinable to include an external thread I2 and above the latter an enlarged head M. As, in mounting the device as above, such mounting is now intended to be had by way of a suitable hole drilled and tapped through a bounding wall of the engines cavitation means for its cooling liquid, with the thread in said hole matching the thread l2, the head 14 may be recessed for application of a spanner wrench, or, as indicated in dot and dash at M in Fig. 2, it may be shaped like a hexagonal nut or one of other shape, as, for instance, of another polygonal cross-section;

Suitably and in an air tight manner secured at its lower portion in the upper" interior of the shell I i, as by being molded in situ, is a main top insulator member l5; with therebelow a pair of suitably spaced insulator members l6 and it each shown as in the form of'aplane disk; These insulator members and H are suitably and also each in an air-tight manner secured across a shell I l.

Two terminals l9 and 20 are projected above the top of the main insulator member 15. The

terminal 20 is provided at the upper end of an electrode-like round rod 2| passing through the insulator member l and there embedded in the latter in an air-tight manner. Below said member E5, the rod 2! passes through an accommodating aperture in the insulator disk 16, and therebelow extends down to the disk [1, against the upper surface of which lies a flattened offset foot portion 22 of said rod.

A bimetallic and hence thermostatically acting element 23 is provided, this preferably longitudinally variously extending as shown in Fig. 3; said element having a straight foot portion for fiatwisely overlying the foot portion 22 of the rod 2!. With matching apertures through these parts, that is, the last-named foot portion, the foot portion 22 of the rod 2|, and the insulator disk IT, a rivet 25 is applied to lock said parts together.

i The two contacts included in the device, and normally touching each other, comprise a buttonlike contact 25 secured to the top of the element 23, and a like contact 26 fixed on the lower end of a fairly short slide-rod or stem 2? having at its top an enlarged head 28; the insulator disk I6 being apertured to allow easy up and down movement of said stem.

vThe terminal i9 is constituted by an upper end portion of an electrode-like round rod 29 also passing through the insulator member i5 and there embedded in the latter in an air-tight manner. This rod 29 extends down to and through the insulator disk l6, by way of a suitable aperture therethrough, and below this aperture the rod 29 is provided with an offset foot portion 30 apertured in line with the aperture in said disk it provided for the stem 21.

Sleeved about said stem, between said foot portion 30 of the rod 29 and the upper contact 25, is an expansile coil spring 3 i.

As will be understood, the rods 2! and 29 and the stem 27 are of electrically conductive material.

In Fig. 2, diagrammatically indicated respectively at 32, 33, 34 and 35, are an ignition switch, a lead therefrom, a coil, and a lead thereto.

In Fig. 4, a motor block is indicated at 36, two of its cylinders at 31, the cylinder caps at 38, the top casting at 39, and the usual water jacket at 40.

As the heat in the cooling liquid rises, the element 23 gradually becomes more and more shortened in the direction of length of the cup 58; but the contacts 25 and 26 do not separate, due to the action of the spring 30. The tension of such spring may be such, for example, that its expansive function ceases when, due to the ascertained rate of heat-eifected temporary distortion of the element 23, the two contacts have moved in unison to the extent representing the attainment of a dangerous temperature by the liquid 40, as, for example, a temperature of 200 F. Thereupon, the contact 25 will move away from the contact 26; and electrical connection between the terminals 19 and 20 will be broken.

Consequently, the spark-plugs of the engine will no longer spark and the engine will stop running; because, as will be noted from Fig. 2,

4 the now closed ignition switch 32 is connected by the lead 33 to the terminal 20, and the terminal I9 is connected to the coil 34 by the lead 35, and there is no connection between said switch and coil shunting the contacts 25 and 26.

Referring to Fig. 5, wherein the parts to which are applied reference numerals with primes added correspond, respectively, to the parts to which have been applied the same numerals without primes, the cup 58 is shown as formed to include a tiny depending neck 4! for facilitating the establishment of a high degree of vacuum in the interior of the device, thereby absolutely to preclude any oxidation at the contacts 25 and 26. This neck is shown as externally threaded, as

for application of a suction hose $2 or the like.

Following air evacuation from the device, and before unscrewing the hose to remove it, the root portion of said neck may be pinched, crimped or otherwise permanently closed in an air-tight manner. The efiicacy to the extent just indicated of a pinching or like operation of the root portion of the neck 4| may be depended on, without the use of auxiliary means or an auxiliary agent such as a spot or shot welding, if the cup I8 is drawn from copper or the like; such material, incidentally, being highly desirable because of its high heat conductivity.

In order to evacuate the desired air from the entirety of the interior of the device, and this at one operation, an aperture may be provided in the disk II as indicated at 43.

While I have illustrated and described the preferred embodiments of my invention, it is to be understood that I do not limit myself to the precise constructions herein disclosed and the right i is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims. 7

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is:

1. Switch means for a safety switch having an externally threaded tubular main shell for mounting through the wall of the water jacket of a liquid cooled engine with the outer end of the shell closed by an insulation member and its inner end closed by a cup-shaped member of high heat conductive material, spaced insulation discs mounted across the interior of the cup-shaped member, spaced parallel conductor rods mounted eccentrically through the insulation member and the one insulation disc adjacent the insulation member, one of said rods having a right angularly bent foot portion on its inner end secured to the adjacent face of the other insulation disc, a right angularly bent foot portion formed on the inner end of the other of said rods closely adjacent the face of the said one insulation disc facing the said other insulation disc, a contact slidably mounted on the foot portion of the said other rod to move axially toward and away from the foot portion of the said one rod, an elongated heat sensitive element having one end secured to the foot portion of said one rod with its other end bent to engage said contact so that as said element becomes heated its said other end moves away from said contact, means resiliently urging said contact to follow movements of the said other end of said element, means limiting the action of said resilient means so that the said other end of said element moves away from said contact when excessive temperatures cause excessive movement of the said other end of said element. V

2. Switch means for a safety switch having an' externally threaded tubular main shell for mounting through the wall of the water jacket of a liquid cooled engine with the outer end 'of the shell closed by an insulation member and its inner end closed by a cup-shaped member of high heat conductive material, spaced insulation discs mounted across the interior of the cupshaped member, spaced parallel conductor rods mounted eccentrically through the insulation member and the one insulation disc adjacent the insulation member, one of said rods having a right angularly bent foot portion on its inner end secured to the adjacent face of the other insulation disc, a right angularly bent foot portion formed on the inner end of the other of said rods closely adjacent the face of the said one insulation disc facing the said other insulation disc, a contact slidably mounted on the foot portion of the said other rod to move axially toward and away from the foot portion of the said one rod, an elongated heat sensitive element having one end secured to the foot portion of said one rod with its other end bent to engage said contact so that as said element becomes heated its said other end moves away from said contact, means resiliently urging said contact to follow movements of the said other end of said element, means limiting the action of said resilient means so that the said other end of said element moves away from said contact when tion of the said other red and the said one insu- I lation disc, and a contact member on the end of said stem adjacent the foot portion of said other rod.

3. Switch means for a safety switch having. an externally threaded tubular main shell for mounting through the Wall of the water jacket of a liquid cooled engine with the outer end of the shell closed by an insulation member and its inner end closed by a cup-shaped member of high heat conductive material, space-d insulation discs mounted across the interior of the cup-shaped member, spaced parallel conductor rods mounted eccentrically through the insulation member and the one insulation disc adjacent the insulation member, one of said rod having a right angularly bent foot portion on its inner end secured t the adjacent face of the other insulation disc, a right angularly bent foot portion formed on the inner end of the other of said rods closely adjacent the face of the said one insulation disc facing the said other insulation disc, a contact slidably mounted on the foot portion of the said other rod to move axially toward and away from the foot portion of the said one rod, an elongated heat sensitive element having one end secured to the foot portion of said one rod with its other end bent to engage said contact so that as said element becomes heated its said other end moves away from said contact, means resiliently urging said contact to follow movements of the said other end of said element, means limiting the action of said resilient means so that the said other end of said element moves away from said contact when excessive temperatures cause excessive movement of the said other end of said element, said contact comprising a conductive stem slidably mounted through aligned holes in the foot portion of the said other red and the said one insulation disc, and a contact member on the end of said stem adjacent the foot portion of said other rod,

6 r anda contact member mounted on the said other end of said element for engaging said first-mentioned contact member.

a; Switch means for a safety switch having an externally threaded tubular main shell for mounting through the wall of the water jacket of a liquid cooled engin with the outer end of the shell closed by an insulation member and its inner end closed by a cup-shaped member of high, heat conductive material, spaced insulation discs mounted across the interior of the cup-shaped member, spaced parallel conductor rods mounted eccentrically through the insulation vmemberand the one insulation disc adjacent the insulation member, one of said rods having a right angularly bent foot portion on its irmer end secured to the adjacent face of the other insulation disc, a right angularly bent foot portion formed on the inner end of the other of said rods closely adjacent the face of the said one insulation disc facing the said other insulation disc, a contact slidably mounted on the foot portion of the said other rod to move axially-toward and away from the foot portion of the said one rod, an elongated heat sensitive element having one end secured to the foot portion of said one rod with its other end bent to engage said contact so that as said element becomes heated its said other end moves away from said contact, means resiliently urging said contact to follow movements of the said other end of said element, means limiting the action of said resilient means so that the said other end of said element moves away from said contact when excessive temperatures cause excessive movement of the said other end of said element, said contact comprising a conductive stem slidably mounted through aligned holes in the foot portion of the said other rod and the said one insulation disc, and a contact member on the end of said stem adjacent the foot portion of said other rod, said resilient means comprising an expansion spring coaxially wound on said stem and operating between the adjacent faces of said contact member and the foot portion of said other rod.

5. Switch means for a safety switch having an externally threaded tubular main shell for mounting through the wall of the water jacket of a liquid cooled engine with the outer end of the shell closed by an insulation member and its inner end closed by a cup-shaped member of high heat conductive material, spaced insulation discs mounted across the interior of the cup-shaped member, spaced parallel conductor rods mounted eccentrically through the insulation member and the one insulation disc adjacent the insulation member, one of said rods having a right angularly bent foot portion on its inner end secured to the adjacent face of the other insulation disc, a right angularly bent foot portion formed on the inner end of the other of said rods closely adjacent the face of the said one insulation disc facing the said other insulation disc, a contact slidably mounted on the foot portion of the said other rod to move axially toward and away from the foot portion of the said one rod, an elongated heat sensitive element having one end secured to the foot portion of said one rod with its other end bent to engage said contact so that as said element becomes heated its said other end moves away from said contact, means resiliently urging said contact to follow movements of the said other end of said element, mean limiting the action of said resilient means so that the said other end of said element moves away from said contact when excessive temperatures cause excessive movement of the said other end of said element, saidcontact comprising a conductive stem s'lidably mounted through aligned holes in the foot portion of the said other rod and the said Q REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Denison Jan. 14, 1919 Ruediger Feb. 12, 1924 Sanders July 9, 1929 Fonseca Mar. 18, 1930 Appelberg Mar. 29, 1932 

